It may be desirable to allow the temperature of a principal residence vary to an extreme limit when the principal residence is unoccupied by virtue of the occupants being on a business or vacation trip, or residing at a recreational residence (such as a ski or shore cottage). With dual residences, the temperature of either of the residences is typically allowed to range to some extreme limit when unoccupied, yet it is desired to be within a comfort limit when occupied.
It is known to allow the temperature of an unoccupied hotel room to deviate significantly from that which is comfortable for occupants. Typical systems utilize telephone lines or auxiliary telephone lines to control units in the individual rooms. These systems utilize auxiliary thermostats (in addition to those used in the HVAC to control comfortable temperatures) for the enablement of the HVAC system. Systems of this type are shown in U.S. Pat. Nos. 4,021,615; 4,107,466; 4,174,064.
In a residence, the situation is somewhat different because the occupied/unoccupied status of the residence is not monitored by personnel within the same building (as is the case in hotels), and therefore the temperature conditions for an unoccupied room cannot be changed to the desired temperature conditions for an occupied room while the intended occupants are not present. Instead, the adjustment of temperature within the space must await the return of the intended occupants. Such systems have the failing that they do not anticipate the re-occupation of a room, but simply begin the process of temperature correction once the room is designated as occupied.
The foregoing systems, therefore, are useless in assisting in the control of temperatures in residences. Some systems are known for monitoring and controlling various devices and/or conditions within a residence. Typically, these are wired systems which are difficult or impossible to put in place except at the time of construction of a residence. Additionally, such systems do not address the needs of a typical homeowner, because these systems are extremely complex, and have only a limited capability for affecting the system remotely (such as by means of telephone). Examples of such systems are U.S. Pat. No. 4,174,517 and U.S. Pat. No. 4,665,544.